Extract _ListTaskInputMixin and allow chaining.

pkg/analyzer/lib/task/model.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analyzer.task.model;
 
 import 'dart:collection';
 
 import 'package:analyzer/src/generated/engine.dart' hide AnalysisTask;
 import 'package:analyzer/src/generated/java_engine.dart';
@@ skipping 261 matching lines @@
  * A description of an input to an [AnalysisTask] that can be used to compute
  * that input.
  *
  * Clients are not expected to subtype this class.
  */
 abstract class ListTaskInput<E> extends TaskInput<List<E>> {
   /**
    * Return a task input that can be used to compute a list whose elements are
    * the result of passing the elements of this input to the [mapper] function.
    */
-  TaskInput<List /*<V>*/ > toList(UnaryFunction<E, dynamic /*<V>*/ > mapper);
+  ListTaskInput /*<V>*/ toList(UnaryFunction<E, dynamic /*<V>*/ > mapper);
 
   /**
    * Return a task input that can be used to compute a list whose elements are
    * [valueResult]'s associated with those elements.
    */
-  TaskInput<List /*<V>*/ > toListOf(ResultDescriptor /*<V>*/ valueResult);
+  ListTaskInput /*<V>*/ toListOf(ResultDescriptor /*<V>*/ valueResult);
 
   /**
    * Return a task input that can be used to compute a map whose keys are the
    * elements of this input and whose values are the result of passing the
    * corresponding key to the [mapper] function.
    */
   TaskInput<Map<E, dynamic /*V*/ >> toMap(
       UnaryFunction<E, dynamic /*<V>*/ > mapper);
 
   /**
@@ skipping 136 matching lines @@
    * be computed, or `false` if the inputs have been computed.
    *
    * It is safe to invoke [moveNext] after it has returned `false`. In this case
    * [moveNext] has no effect and will again return `false`.
    *
    * Throws a [StateError] if the value of the current result has not been
    * provided using [currentValue].
    */
   bool moveNext();
 }